U.S. patent application number 12/026181 was filed with the patent office on 2008-08-14 for method of driving plasma display apparatus.
Invention is credited to Byungjoon Rhee.
Application Number | 20080191973 12/026181 |
Document ID | / |
Family ID | 39685410 |
Filed Date | 2008-08-14 |
United States Patent
Application |
20080191973 |
Kind Code |
A1 |
Rhee; Byungjoon |
August 14, 2008 |
METHOD OF DRIVING PLASMA DISPLAY APPARATUS
Abstract
A method of driving a plasma display apparatus is disclosed. The
method includes supplying a first reset signal to a scan electrode
during a reset period of a first subfield of a plurality of
subfields of a frame, and supplying a second reset signal, whose a
peak voltage is lower than a peak voltage of the first reset
signal, to the scan electrode during reset periods of the remaining
subfields except the first subfield when a data signal is not
supplied to the address electrode during address periods of the
remaining subfields. The first subfield is first arranged in the
plurality of subfields in time order.
Inventors: |
Rhee; Byungjoon; (Seoul,
KR) |
Correspondence
Address: |
KED & ASSOCIATES, LLP
P.O. Box 221200
Chantilly
VA
20153-1200
US
|
Family ID: |
39685410 |
Appl. No.: |
12/026181 |
Filed: |
February 5, 2008 |
Current U.S.
Class: |
345/67 |
Current CPC
Class: |
G09G 3/2927 20130101;
G09G 2320/0238 20130101 |
Class at
Publication: |
345/67 |
International
Class: |
G09G 3/28 20060101
G09G003/28 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 9, 2007 |
KR |
10-2007-0014010 |
Claims
1. A method of driving a plasma display apparatus including a scan
electrode and a sustain electrode positioned substantially parallel
to each other, and an address electrode positioned to intersect the
scan electrode and the sustain electrode, the method comprising;
supplying a first reset signal to the scan electrode during a reset
period of a first subfield of a plurality of subfields of a frame,
the first subfield being first arranged in the plurality of
subfields in time order; and supplying a second reset signal, whose
a peak voltage is lower than a peak voltage of the first reset
signal, to the scan electrode during reset periods of the remaining
subfields except the first subfield when a data signal is not
supplied to the address electrode during address periods of the
remaining subfields.
2. The method of claim 1, wherein the first reset signal includes a
rising signal that gradually rises from a first voltage higher than
a ground level voltage to a second voltage, and a falling signal
that gradually falls from a third voltage lower than the second
voltage to a fourth voltage lower than the ground level voltage,
and the second reset signal includes a falling signal that
gradually falls from a fifth voltage higher than the ground voltage
to a sixth voltage lower than the ground level voltage, and the
second reset signal does not include a rising signal with a
gradually rising voltage.
3. The method of claim 2, wherein the third voltage is
substantially equal to the fifth voltage.
4. The method of claim 3, wherein the third and fifth voltages are
substantially equal to a voltage of a sustain signal supplied to at
least one of the scan electrode or the sustain electrode during a
sustain period following the address period.
5. The method of claim 2, wherein the fourth voltage is
substantially equal to the sixth voltage.
6. The method of claim 2, wherein the fourth voltage and the sixth
voltage are higher than a lowest voltage of a scan signal supplied
to the scan electrode during the address period.
7. The method of claim 1, wherein the first subfield has a lowest
gray level weight.
8. A method of driving a plasma display apparatus including a scan
electrode and a sustain electrode positioned substantially parallel
to each other, and an address electrode positioned to intersect the
scan electrode and the sustain electrode, the method comprising:
supplying a first reset signal, that includes a rising signal with
a gradually rising voltage and a falling signal with a gradually
falling voltage, to the scan electrode during a reset period of a
first subfield of a plurality of subfields of a frame, the first
subfield being first arranged in the plurality of subfields in time
order; when a data signal is supplied to the address electrode
during an address period of at least one of the remaining subfields
except the first subfield, supplying a third reset signal including
a rising signal with a gradually rising voltage and a falling
signal with a gradually falling voltage to the scan electrode
during a reset period of at least one of the at least one subfield
to which the data signal is supplied, and supplying a second reset
signal, whose a peak voltage is lower than a peak voltage of the
first reset signal, to the scan electrode during reset periods of
the remaining subfields except the subfields in which the first and
third reset signals are supplied; and supplying a second reset
signal, whose a peak voltage is lower than a peak voltage of the
first reset signal, to the scan electrode during the reset periods
of the remaining subfields except the first subfield when a data
signal is not supplied to the address electrode during address
periods of the remaining subfields except the first subfield.
9. The method of claim 8, wherein the second reset signal includes
a falling signal with a gradually falling voltage, and does not
include a rising signal with a gradually rising voltage.
10. The method of claim 9, wherein the rising signal of the first
reset signal gradually rises from a first voltage higher than a
ground level voltage to a second voltage, and the falling signal of
the first reset signal gradually falls from a third voltage lower
than the second voltage to a fourth voltage lower than the ground
level voltage, the falling signal of the second reset signal
gradually falls from a fifth voltage higher than the ground level
voltage to a sixth voltage lower than the ground level voltage, and
the rising signal of the third reset signal gradually rises from a
seventh voltage higher than the ground level voltage to an eighth
voltage, and the falling signal of the third reset signal gradually
falls from a ninth voltage higher than the ground level voltage to
a tenth voltage lower than the ground level voltage.
11. The method of claim 10, wherein the third, fifth, and ninth
voltages are substantially equal to one another.
12. The method of claim 11, wherein the third, fifth, and ninth
voltages are substantially equal to a voltage of a sustain signal
supplied to at least one of the scan electrode or the sustain
electrode during a sustain period following the address period.
13. The method of claim 10, wherein the fourth, sixth, and tenth
voltages are substantially equal to one another.
14. The method of claim 2, wherein the fourth, sixth, and tenth
voltages are higher than a lowest voltage of a scan signal supplied
to the scan electrode during the address period.
15. The method of claim 10, wherein the eighth voltage is
substantially equal to or lower than the second voltage.
16. The method of claim 10, wherein the first subfield has a lowest
gray level weight.
17. A method of driving a plasma display apparatus including a scan
electrode and a sustain electrode positioned substantially parallel
to each other, and an address electrode positioned to intersect the
scan electrode and the sustain electrode, the method comprising:
supplying a first reset signal to the scan electrode during a reset
period of a first subfield of a plurality of subfields of a frame
when all the subfields of the frame are turned off, the first
subfield being first arranged in the plurality of subfields in time
order; and supplying a second reset signal, whose a peak voltage is
lower than a peak voltage of the first reset signal, to the scan
electrode during reset periods of the remaining subfields except
the first subfield when all the subfields of the frame are turned
off.
18. The method of claim 17, wherein the first reset signal includes
a rising signal that gradually rises from a first voltage higher
than a ground level voltage to a second voltage, and a falling
signal that gradually falls from a third voltage lower than the
second voltage to a fourth voltage lower than the ground level
voltage, and the second reset signal includes a falling signal that
gradually falls from a fifth voltage higher than the ground voltage
to a sixth voltage lower than the ground level voltage, and the
second reset signal does not include a rising signal with a
gradually rising voltage.
19. The method of claim 10, wherein the third voltage is
substantially equal to the fifth voltage.
20. The method of claim 17, wherein the first subfield has a lowest
gray level weight.
Description
[0001] This application claims the benefit of Korean Patent
Application No. 10-2007-0014010 filed on Feb. 9, 2007, which is
hereby incorporated by reference.
BACKGROUND
[0002] 1. Field
[0003] An exemplary embodiment relates to a method of driving a
plasma display apparatus.
[0004] 2. Description of the Background Art
[0005] Out of display apparatuses, a plasma display apparatus
includes a plasma display panel and a driver for driving the plasma
display panel.
[0006] The plasma display panel has the structure in which barrier
ribs formed between a front panel and a rear panel forms unit
discharge cell or discharge cells. Each discharge cell is filled
with an inert gas containing a main discharge gas such as neon
(Ne), helium (He) or a mixture of Ne and He, and a small amount of
xenon (Xe).
[0007] The plurality of discharge cells form one pixel. For
example, a red (R) discharge cell, a green (G) discharge cell, and
a blue (B) discharge cell form one pixel.
[0008] When the plasma display panel is discharged by a high
frequency voltage, the inert gas generates vacuum ultraviolet rays,
which thereby cause phosphors formed between the barrier ribs to
emit light, thus displaying an image. Since the plasma display
panel can be manufactured to be thin and light, it has attracted
attention as a next generation display device.
[0009] Because a rising signal supplied to a scan electrode during
a reset period is a high-voltage signal, the quantity of light
generated by a discharge generated by the rising signal relatively
increases.
[0010] Thus, a luminance (i.e., a black level luminance) in an OFF
state of all the discharge cells of the plasma display panel
relatively increases. This results in a degradation of a contrast
characteristic and the generation of image retention.
[0011] Accordingly, a method to apply the rising signal in only one
subfield of one frame was proposed, and thus can partially improve
the contrast characteristic. However, an erroneous discharge
occurred at a specific gray level.
SUMMARY
[0012] In one aspect, a method of driving a plasma display
apparatus including a scan electrode and a sustain electrode
positioned substantially parallel to each other, and an address
electrode positioned to intersect the scan electrode and the
sustain electrode, the method comprises supplying a first reset
signal to the scan electrode during a reset period of a first
subfield of a plurality of subfields of a frame, the first subfield
being first arranged in the plurality of subfields in time order,
and supplying a second reset signal, whose a peak voltage is lower
than a peak voltage of the first reset signal, to the scan
electrode during reset periods of the remaining subfields except
the first subfield when a data signal is not supplied to the
address electrode during address periods of the remaining
subfields.
[0013] In another aspect, a method of driving a plasma display
apparatus including a scan electrode and a sustain electrode
positioned substantially parallel to each other, and an address
electrode positioned to intersect the scan electrode and the
sustain electrode, the method comprises supplying a first reset
signal, that includes a rising signal with a gradually rising
voltage and a falling signal with a gradually falling voltage, to
the scan electrode during a reset period of a first subfield of a
plurality of subfields of a frame, the first subfield being first
arranged in the plurality of subfields in time order, when a data
signal is supplied to the address electrode during an address
period of at least one of the remaining subfields except the first
subfield, supplying a third reset signal including a rising signal
with a gradually rising voltage and a falling signal with a
gradually falling voltage to the scan electrode during a reset
period of the at least one subfield to which the data signal is
supplied, and supplying a second reset signal, whose a peak voltage
is lower than a peak voltage of the first reset signal, to the scan
electrode during reset periods of the remaining subfields, and
supplying a second reset signal, whose a peak voltage is lower than
a peak voltage of the first reset signal, to the scan electrode
during the reset periods of the remaining subfields when a data
signal is not supplied to the address electrode during address
periods of the remaining subfields.
[0014] In yet another aspect, a method of driving a plasma display
apparatus including a scan electrode and a sustain electrode
positioned substantially parallel to each other, and an address
electrode positioned to intersect the scan electrode and the
sustain electrode, the method comprises supplying a first reset
signal to the scan electrode during a reset period of a first
subfield of a plurality of subfields of a frame in a state where
all the subfields of the frame are turned off, the first subfield
being first arranged in the plurality of subfields in time order,
and supplying a second reset signal, whose a peak voltage is lower
than a peak voltage of the first reset signal, to the scan
electrode during reset periods of the remaining subfields except
the first subfield in a state where all the subfields of the frame
are turned off.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated on and
constitute a part of this specification, illustrate embodiments of
the invention and together with the description serve to explain
the principles of the invention. In the drawings:
[0016] FIG. 1 illustrates a plasma display panel according to an
exemplary embodiment;
[0017] FIG. 2 illustrates a method for representing a gray level of
an image in the plasma display panel according to the exemplary
embodiment;
[0018] FIG. 3 illustrates a plasma display apparatus according to
the exemplary embodiment;
[0019] FIG. 4 illustrates a method of driving a plasma display
apparatus according to a first embodiment;
[0020] FIG. 5 illustrates a method of driving a plasma display
apparatus according to a second embodiment;
[0021] FIG. 6 is a diagram for comparing areas A and B of FIG.
5;
[0022] FIG. 7 is a diagram for explaining in detail a first
subfield in a method of driving a plasma display apparatus
according to a third embodiment;
[0023] FIGS. 8A and 8B are diagrams for explaining an example of a
case where a second reset signal is omitted;
[0024] FIGS. 9 and 10 are diagrams for explaining in detail a first
reset signal and a third reset signal;
[0025] FIG. 11 illustrates a method of driving a plasma display
apparatus according to a fourth embodiment;
[0026] FIG. 12 is a diagram for explaining in detail an area A of
FIG. 11;
[0027] FIG. 13 illustrates a method of driving a plasma display
apparatus according to a fifth embodiment;
[0028] FIG. 14 is a diagram for explaining in detail an area B of
FIG. 11;
[0029] FIGS. 15A to 15C illustrate a method of driving a plasma
display apparatus according to a sixth embodiment;
[0030] FIG. 16 illustrates a method of driving a plasma display
apparatus according to a seventh embodiment;
[0031] FIG. 17 is a diagram for explaining in detail an area A of
FIG. 16; and
[0032] FIGS. 18A and 18B are diagrams for explaining in detail a
driving waveform depending on the method of driving the plasma
display apparatus according to the seventh embodiment.
DETAILED DESCRIPTION
[0033] Reference will now be made in detail embodiments of the
invention examples of which are illustrated in the accompanying
drawings.
[0034] FIG. 1 illustrates a plasma display panel according to an
exemplary embodiment.
[0035] As shown in FIG. 1, the plasma display panel includes a
front panel 100 and a rear panel 110 which coalesce with each
other. The front panel 100 includes a front substrate 101 which is
a display surface. The rear panel 110 includes a rear substrate 111
constituting a rear surface. A plurality of scan electrodes 102 and
a plurality of sustain electrodes 103 are formed in pairs on the
front substrate 101, on which an image is displayed, to form a
plurality of maintenance electrode pairs. A plurality of address
electrodes 113 are arranged on the rear substrate 111 to intersect
the plurality of maintenance electrode pairs.
[0036] The scan electrode 102 and the sustain electrode 103 each
include transparent electrodes 102a and 103a made of a transparent
indium-tin-oxide (ITO) material and bus electrodes 102b and 103b
made of a metal material. The scan electrode 102 and the sustain
electrode 103 generate a mutual discharge therebetween in one
discharge cell and maintain light-emissions of discharge cells.
[0037] The scan electrode 102 and the sustain electrode 103 are
covered with one or more upper dielectric layers 104 for limiting a
discharge current and providing insulation between the maintenance
electrode pairs. A protective layer 105 with a deposit of magnesium
oxide (MgO) is formed on the upper dielectric layer 104 to
facilitate discharge conditions.
[0038] A plurality of stripe-type or well-type barrier ribs 112 are
formed parallel to each other on the rear substrate 111 of the rear
panel 110 to form a plurality of discharge spaces, i.e., a
plurality of discharge cells. The plurality of address electrodes
113 are positioned parallel to the barrier ribs 112 to perform an
address discharge which cause the inert gas to generate vacuum
ultraviolet rays.
[0039] An upper surface of the rear substrate 111 is coated with
red (R), green (G) and blue (B) phosphors 114 for emitting visible
light for an image display during the generation of the sustain
discharge. A lower dielectric layer 115 is formed between the
address electrodes 113 and the phosphors 114 to protect the address
electrodes 113.
[0040] In the plasma display panel having the above-described
structure, the plurality of discharge cells are formed in a matrix
form. A driver including a driving circuit for applying a
predetermined signal to the discharge cells is attached to the
plasma display panel to drive the plasma display panel.
[0041] FIG. 2 illustrates a method for representing a gray level of
an image in the plasma display panel according to the exemplary
embodiment.
[0042] As shown in FIG. 2, the plasma display panel is driven with
a frame being divided into a plurality of subfields having a
different number of emission times. Each subfield is subdivided
into a reset period for uniformly generating a discharge, an
address period for selecting a discharge cell, and a sustain period
for representing a gray level in accordance with the number of
discharges.
[0043] For example, if an image with 256-gray level is to be
displayed, a frame period (for example, 16.67 ms) corresponding to
1/60 sec is divided into eight subfields SF1 to SF8. Each of the
eight subfields SF1 to SF8 is subdivided into a reset period, an
address period, and a sustain period.
[0044] A duration of the reset period in a subfield is equal to a
duration of the reset periods in the other subfields. A duration of
the address period in a subfield is equal to a duration of the
address periods in the other subfields. However, a duration of the
sustain period of each subfield may be different from one another,
and the number of sustain signals assigned during the sustain
period of each subfield may be different from one another. For
example, the sustain period increases in a ratio of 2.sup.n (where,
n=0, 1, 2, 3, 4, 5, 6, 7) in each of the subfields. Although the
above description has been made with respect to a case where one
frame includes 8 subfields, it is not limited thereto. One frame
may include 10 to 12 subfields.
[0045] FIG. 3 illustrates a plasma display apparatus according to
the exemplary embodiment.
[0046] As shown in FIG. 3, the plasma display apparatus according
to the exemplary embodiment includes a plasma display panel 300
including a scan electrode, a timing controller 301, a data driver
302, a scan driver 303, a sustain driver 304, and a subfield
mapping unit 305.
[0047] The timing controller 301 receives a vertical/horizontal
synchronization signal and a predetermined clock signal. The
controller 121 generates timing control signals CTRX. CTRY and CTRZ
for controlling each of the drivers 302, 303 and 304, and applies
the timing control signals CTRX, CTRY and CTRZ to the corresponding
drivers 302, 303 and 304, respectively.
[0048] Accordingly, the timing controller 301 controls operations
of the drivers 302, 303 and 304. Further, the timing controller 301
controls the scan driver 303 to apply a reset signal including only
a falling signal to the scan electrodes Y1 to Yn during a portion
of a plurality of subfields. This results in the prevention of an
erroneous discharge caused by an unstable discharge.
[0049] The data driver 122 applies a data signal, which is sampled
and latched in response to the timing control signal CTRX received
from the timing controller 301, to the address electrodes X1 to
Xm.
[0050] Under the control of the timing controller 301, the scan
driver 303 controls the reset signal supplied to the scan
electrodes Y1 to Yn during a reset period.
[0051] Under the control of the timing controller 301, the scan
driver 303 consecutively applies scan signals with a scan voltage
-Vy to the scan electrodes Y1 to Yn during an address period.
[0052] Under the control of the timing controller 301, the sustain
driver 304 applies a bias voltage of a sustain voltage Vs to the
sustain electrodes Z during a set-down period of the reset period
and the address period. The scan driver 303 and the sustain driver
304 alternatively operate during a sustain period to apply a
sustain signal to the scan electrodes Y1 to Yn and the sustain
electrodes Z.
[0053] The last sustain discharge ends in one subfield, and then
the sustain driver 304 may apply an erase signal to the sustain
electrodes Z.
[0054] The subfield mapping unit 305 maps video data, which is
processed through a predetermined imaging process, for each
subfield, and then outputs the mapped video data.
[0055] For example, the subfield mapping unit 305 maps video data
for each subfield, after performing a motion process, an average
power level (APL) process, an half-tone correction process, and the
like, on video data input from an external signal processor (not
shown), for example, a video signal controller (VSC) chip (not
shown). Then, the subfield mapping unit 305 produces the mapped
video data and outputs it.
[0056] FIG. 4 illustrates a method of driving a plasma display
apparatus according to a first embodiment.
[0057] As shown in FIG. 4, the driving method of the plasma display
apparatus according to the first embodiment displays an image
during a plurality of frames, and each frame is divided into a
plurality of subfields having a different number of emission times.
Each frame may be divided into 10 or 12 subfields having a
different number of emission times.
[0058] The driving method according to the first embodiment is
preformed with each subfield being subdivided into a reset period
for initializing the whole screen, an address period for selecting
cells to be discharged, a sustain period for maintaining discharges
of the selected cells, and an erase period for erasing wall charges
within the discharged cells.
[0059] The driving method according to the first embodiment
includes applying a first reset signal RP1 including a rising
signal and a falling signal to the scan electrode during a reset
period of a subfield (for example, a first subfield SF1) of the
lowest gray level weight, and applying a third reset signal RP3
including only a falling signal to the scan electrode in a subfield
except the first subfield SF1.
[0060] The falling signal of third reset signal RP3 is maintained
at a sustain voltage Vs being a bias voltage, and then falls from
the sustain voltage Vs. A contrast characteristic is improved by
reducing the number of applications of a rising signal with a high
voltage.
[0061] In case that a rising signal is supplied once during one
frame, an erroneous discharge may occur at a specific gray level.
To prevent the erroneous discharge, a second reset signal RP2
including a rising signal and a falling signal is supplied to the
scan electrode during a reset period of a turn-on subfield next to
a turn-off subfield.
[0062] For example, in case that all subfields of one frame are
turned on, one subfield of subfields with a relative low gray level
weight may be unstable. However, since all the subfields following
the unstable subfield have been turned on, a stable discharge
occurs due to discharges of many sustain signals.
[0063] However, as shown in FIG. 4, if three subfields SF1-SF3 in
subfields SF1-SF5 of a relative low gray level weight are turned on
and the fifth subfield SF5 is turned on, the number of sustain
signals generated in the subfields following the turn-on subfield
SF3 is not sufficient. This results in the generation of an
erroneous discharge in the turn-on subfield SF5.
[0064] The generation of an erroneous discharge in the turn-on
subfield SF5 is prevented by applying the second reset signal RP2
including the rising signal and the falling signal in the turn-on
subfield SF5 next to the unstable subfield SF3.
[0065] Although the subfields SF1, SF2, SF3 and SF5 as a turn-on
subfield were optionally set in FIG. 4 for the easy explanation,
the first embodiment is not limited thereto.
[0066] For example, it is assumed that the first subfield SF1 is
turned on and the fifth subfield SF5 is turned on again, the third
reset signal RP3 including only the falling signal is supplied
during reset periods of the second to fourth subfields SF2-SF4.
Therefore, it is a great likelihood of the generation of an
erroneous discharge in the fifth subfield SF5.
[0067] Accordingly, the second reset signal RP2 including the
rising signal and the falling signal is supplied in the fifth
subfield SF5 such that the generation of the erroneous discharge is
prevented in the fifth subfield SF5.
[0068] In the first embodiment, the subfields during which the
third reset signal RP3 is supplied may be a low gray level
subfield. The low gray level subfield may range from the first to
fourth subfields SF1-SF4 in the subfields SF1-SF12 of one frame
arranged in an increasing order of gray level weight.
[0069] The subfields during which the second reset signal RP2 is
supplied may range from the fifth to twelfth subfields SF5-SF12 in
the subfields SF1-SF12 of one frame arranged in an increasing order
of gray level weight.
[0070] If the first reset signal RP1 including the rising signal
and the falling signal is supplied in the subfield SF1 of the
lowest gray level and the third reset signal RP3 including only the
falling signal is supplied in the first to fourth subfields SF1-SF4
in the subfields SF1-SF12 of one frame arranged in an increasing
order of gray level weight, it is a great likelihood of the
generation of the erroneous discharge due to the unstable
discharge. Therefore, the second reset signal RP2 is supplied in
the fifth to twelfth subfields SF5-SF12 in the subfields SF1-SF12
of one frame arranged in an increasing order of gray level
weight.
[0071] Accordingly, the number of rising signals supplied during
one frame is reduced considerably such that a contrast
characteristic is improved and an erroneous discharge at a specific
gray level is prevented.
[0072] FIG. 5 illustrates a method of driving a plasma display
apparatus according to a second embodiment.
[0073] As shown in FIG. 5, a first reset signal RP1 and a second
reset signal RP2 are supplied during a reset period of a subfield
SF1 having a lowest gray level weight and a reset period of a
turn-on subfield SF5 next to a turn-off subfield SF4 of a plurality
of subfields SF1-SF12, respectively, so that a peak voltage Vpeak1
of a rising signal of the first reset signal RP1 is higher than a
peak voltage Vpeak2 of a rising signal of the second reset signal
RP2.
[0074] In the first embodiment illustrated in FIG. 4, to prevent
the generation of the erroneous discharge, a peak voltage of the
rising signal of the first reset signal RP1 supplied during the
reset period of the lowest gray level subfield SF1 is equal to a
peak voltage of the rising signal of the second reset signal RP2
supplied during the reset period of the fifth subfield SF5.
However, unlike the first embodiment, in FIG. 5, the generation of
a flicker is prevented by applying the second reset signal RP2
having the peak voltage Vpeak2, that is lower than the peak voltage
Vpeak1 of the first reset signal RP1 supplied during the reset
period of the lowest gray level subfield SF1, during the reset
period of the turn-on subfield SF5 next to the turn-off subfield
SF4.
[0075] FIG. 6 is a diagram for comparing areas A and B of FIG. 5.
As shown in FIG. 6, a rising signal RU of the first reset signal
RP1 may gradually rise from a first voltage V1 higher than a ground
level voltage GND to a second voltage V2. A falling signal RD of
the first reset signal RP1 may gradually fall from a third voltage
V3 lower than the second voltage V2 to a fourth voltage V4 lower
than the ground level voltage GND.
[0076] Further, a rising signal RU of the second reset signal RP2
may gradually rise from a seventh voltage V7 higher than the ground
level voltage GND to an eighth voltage V8. A falling signal RD of
the second reset signal RP2 may gradually fall from a ninth voltage
V9 higher than the ground level voltage GND to a tenth voltage V10
lower than the ground level voltage GND.
[0077] A peak voltage (i.e., the second voltage V2) of the first
reset signal RP1 may be higher than a peak voltage (i.e., the
eighth voltage V8) of the second reset signal RP2.
[0078] The first voltage V1 may be substantially equal to the
seventh voltage V7. The first voltage V1 may be substantially equal
to the third voltage V3. The seventh voltage V7 may be
substantially equal to the ninth voltage V9. The fourth voltage V4
may be substantially equal to the tenth voltage V10. The fourth and
tenth voltages V4 and V10 may be higher than a lowest voltage of
the scan signal supplied to the scan electrode during the address
period.
[0079] FIG. 7 is a diagram for explaining in detail a first
subfield in a method of driving a plasma display apparatus
according to a third embodiment.
[0080] As shown in FIG. 7, before a first reset signal RP1 having a
rising signal and a falling signal is supplied to the scan
electrode during a reset period of a first subfield SF1 as shown in
FIGS. 4 and 5, a first pre-reset signal PRP1 is supplied to the
scan electrode and a second pre-reset signal PRP2 of a polarity
opposite a polarity of the first pre-reset signal PRP1 is supplied
to the sustain electrode correspondingly to the first pre-reset
signal PRP1.
[0081] The first pre-reset signal PRP1 is a negative polarity, and
may be a falling signal gradually falling from a ground level
voltage GND. The second pre-reset signal PRP2 is a positive
polarity and may be a square wave.
[0082] As above, since the first and second pre-reset signals PRP1
and PRP2 are supplied prior to the reset period of the first
subfield SF1, a peak voltage of the rising signal of the first
reset signal RP1 supplied during the reset period of the first
subfield SF1 is lowered. This results in a reduction in a black
level luminance in a reset process.
[0083] FIGS. 8A and 8B are diagrams for explaining an example of a
case where a second reset signal is omitted.
[0084] As shown in FIG. 8A, a first reset signal RP1 is supplied to
the scan electrode during a reset period of a first subfield SF1 of
a plurality of subfields SF1 to SF12 of a frame, and a data signal
is not supplied to the address electrode during address periods of
the remaining subfields SF2 to SF12 except the first subfield SF1.
The first subfield SF1 is first arranged in time order in the
frame. In this case, a third reset signal RP3, whose a peak voltage
is lower than a peak voltage of the first reset signal RP1, is
supplied to the scan electrode during reset periods of the
remaining subfields SF2 to SF12.
[0085] In other words, in case that the first subfield SF1 is
turned on and the remaining subfields SF2 to SF12 are turned off,
the first reset signal RP1 is supplied to the scan electrode in the
first subfield SF1 and the third reset signal RP3 is supplied to
the scan electrode in the remaining subfields SF2 to SF12.
[0086] In case that the remaining subfields SF2 to SF12 are turned
off (i.e., in case that the data signal is not supplied to the
address electrode in the remaining subfields SF2 to SF12), an
address discharge and a sustain discharge do not occur.
[0087] Therefore, there is a small likelihood of the generation of
an unstable discharge. Accordingly, although the third reset signal
RP3 is supplied to the scan electrode in the remaining subfields
SF2 to SF12, the discharge is not unstable. Further, the contrast
characteristic can be further improved.
[0088] As shown in FIG. 8B, all of subfields SF1 to SF12 of a frame
are turned off. In this case, a first reset signal RP1 is supplied
to the scan electrode during a reset period of a first subfield SF1
(first arranged in time order), and a third reset signal RP3, whose
a peak voltage is lower than a peak voltage of the first reset
signal RP1, is supplied to the scan electrode during reset periods
of the remaining subfields SF2 to SF12. Hence, the contrast
characteristic can be further improved.
[0089] FIGS. 9 and 10 are diagrams for explaining in detail a first
reset signal and a third reset signal.
[0090] As shown in FIG. 9, the first reset signal RP1 may include a
rising signal RU which gradually rises from a first voltage V1
higher than the ground level voltage GND to a second voltage V2,
and a falling signal RD which gradually falls from a third voltage
V3 lower than the second voltage V2 to a fourth voltage V4 lower
than the ground level voltage GND.
[0091] Further, the third reset signal RP3 may include a falling
signal RD which gradually falls from a fifth voltage V5 higher than
the ground level voltage GND to a sixth voltage V6 lower than the
ground level voltage GND. The third reset signal RP3 may not
include a rising signal with a gradually rising voltage.
[0092] The third voltage V3 may be substantially equal to the fifth
voltage V5. The fourth voltage V4 may be substantially equal to the
sixth voltage V6. The first voltage V1 may be substantially equal
to the third voltage V3.
[0093] As shown in FIG. 10, the third and fifth voltages V3 and V5
may be substantially equal to a voltage Vs of a sustain signal SUS
supplied to at least one of the scan electrode or the sustain
electrode during a sustain period following the address period.
[0094] The fourth and sixth voltages V4 and V6 may be higher than a
lowest voltage -Vy of a scan signal Scan supplied to the scan
electrode during the address period. Hence, a set-down discharge
can be stabilized.
[0095] FIG. 11 illustrates a method of driving a plasma display
apparatus according to a fourth embodiment.
[0096] As shown in FIG. 11, the driving method of the plasma
display apparatus according to the fourth embodiment displays an
image during a plurality of frames, and each frame is divided into
a plurality of subfields having a different number of emission
times. Each frame may be divided into 10 or 12 subfields having a
different number of emission times.
[0097] The driving method according to the fourth embodiment is
preformed with each subfield being subdivided into a reset period
for initializing the whole screen, an address period for selecting
cells to be discharged, a sustain period for maintaining discharges
of the selected cells, and an erase period for erasing wall charges
within the discharged cells.
[0098] The driving method according to the fourth embodiment
applies a first reset signal RP1 including a rising signal and a
falling signal to the scan electrode during a reset period of each
of subfields SF1-SF12 of a first frame.
[0099] Then, in case that a second frame following the first frame
is an OFF-cell, a second reset signal RP2 including only a falling
signal is supplied to the scan electrode during a reset period of
each of subfields SF1-SF12 of the second frame.
[0100] For example, if the first frame corresponding to a portion
of a display surface (not shown) of the plasma display panel is an
ON-cell, the first reset signal RP1 is supplied in the twelve
subfields SF1-SF12 of the first frame, and the second frame is the
OFF-cell in the whole panel, a window pattern displayed on the
portion of the panel display surface appears as an image retention
pattern.
[0101] Accordingly, when there is a movement from the ON-cell first
frame to the OFF-cell second frame, the second reset signal RP2
including only the falling signal is supplied in all the subfields
SF1 to SF12 of the second frame.
[0102] FIG. 12 is a diagram for explaining in detail an area A of
FIG. 11. As shown in FIG. 12, the second reset signal RP2 supplied
in all the subfields SF1 to SF12 of the second frame includes only
the falling signal.
[0103] The falling signal is maintained at a sustain voltage Vs
being a bias voltage, and then gradually falls from the sustain
voltage Vs.
[0104] As above, since the second reset signal RP2 supplied in the
second frame has a luminance of about 0 cd/m.sup.2 based on one
signal as compared with the first reset signal RP1 having a
luminance of about 0.1 cd/m.sup.2 or more based on one signal, when
there is the movement from the ON-cell first frame to the OFF-cell
second frame the application of the second reset signal RP2 can
lower an image retention level and a contrast characteristic can be
improved.
[0105] FIG. 13 illustrates a method of driving a plasma display
apparatus according to a fifth embodiment, and FIG. 14 is a diagram
for explaining in detail an area B of FIG. 11.
[0106] As shown in FIG. 13, the driving method according to the
fifth embodiment applies a first reset signal RP1 including a
rising signal and a falling signal to the scan electrode during a
reset period of each of subfields SF1-SF12 of a first frame.
[0107] Then, in case that a second frame following the first frame
is an OFF-cell, a second reset signal RP2 including at least two
rising signals is supplied to the scan electrode during reset
periods of all subfields SF1-SF12 of the second frame.
[0108] As shown in FIG. 14, a time period A in all the subfields
SF1-SF12 of the second frame during which one rising signal of the
second reset signal RP2 is supplied is shorter than a time period B
in the subfields SF1-SF12 of the first frame during which the
rising signal of the first reset signal RP1 is supplied.
[0109] The number of rising signals supplied in all the subfields
SF1-SF12 of the second frame may range from 1 to 3 in each subfield
of the second frame.
[0110] Since the rising signals supplied in the subfields of the
first frame has a luminance of about 0.1 cd/m.sup.2 based on one
signal, a flicker may occur due to the luminance deviation when an
ON-cell and an OFF-cell are alternately varied to each other such
that a contrast characteristic may worsen.
[0111] Accordingly, a weak discharge occurs several times by
applying the second reset signal RP2 including the 2 or 3 rising
signals having a luminance of about 0.04 cd/m.sup.2 based on one
signal. As a result, several weak discharges lower a level of dark
image retention as compared with one strong discharge, and the
generation of the flicker due to the luminance deviation is
prevented.
[0112] FIGS. 15A to 15C illustrate a method of driving a plasma
display apparatus according to a sixth embodiment.
[0113] FIG. 15A illustrates a related art reset signal supplied
during a last subfield of a second frame and a first subfield of a
third frame next to the second frame.
[0114] As shown in FIG. 15A, after a second reset signal shown in
FIGS. 11 and 13 is supplied in the second frame, one reset signal
is supplied during a reset period of the first subfield of the
third frame next to the second frame. In this case, it is difficult
to vary a discharge when there is a movement from the OFF-cell
second frame to the ON-cell third frame.
[0115] FIG. 15B illustrates a reset signal according to the sixth
embodiment supplied during a last subfield of a second frame and a
first subfield of a third frame next to the second frame. As shown
in FIG. 15B, a third reset signal RP3 and a fourth reset signal RP4
are supplied in the first subfield of the third frame.
[0116] The third reset signal RP3 and the fourth reset signal RP4
each include a rising signal.
[0117] A first peak voltage Vpeak1 of the third reset signal RP3 is
higher than a second peak voltage Vpeak2 of the fourth reset signal
RP4.
[0118] A difference (Vpeak1-Vpeak2) between the first peak voltage
Vpeak1 and the second peak voltage Vpeak2 may be equal to or less
than 100V.
[0119] As above, since the third reset signal RP3 that is higher
than the fourth reset signal RP4 by 100V or less is supplied, the
unstableness of discharge generated when there is a movement from
the OFF-cell second frame to the ON-cell third frame can be
solved.
[0120] A third reset signal RP3 having a different form from the
third reset signal RP3 shown in FIG. 15B may be supplied. This will
be below described with reference to FIG. 15C.
[0121] As shown in FIG. 15C, the third reset signal RP3 supplied in
the first subfield of the third frame may include a square
wave.
[0122] A voltage of the square wave is equal to the second peak
voltage Vpeak2 of the fourth reset signal RP4. A time period C
during which the square wave of the third reset signal RP3 is
supplied is shorter than a time period D during which the rising
signal of the fourth reset signal RP4 is supplied.
[0123] As above, since the third reset signal RP3 is supplied
during the time period C shorter than the time period D during
which the fourth reset signal RP4 is supplied, the unstableness of
discharge is solved when there is a movement from the OFF-cell
second frame to the ON-cell third frame.
[0124] FIG. 16 illustrates a method of driving a plasma display
apparatus according to a seventh embodiment, and FIG. 17 is a
diagram for explaining in detail an area A of FIG. 16.
[0125] As shown in FIG. 16, the driving method of the plasma
display apparatus according to the seventh embodiment displays an
image during a plurality of frames, and each frame is divided into
a plurality of subfields having a different number of emission
times. Each frame may be divided into 10 or 12 subfields having a
different number of emission times.
[0126] The driving method according to the seventh embodiment is
preformed with each subfield being subdivided into a reset period
for initializing the whole screen, an address period for selecting
cells to be discharged, a sustain period for maintaining discharges
of the selected cells, and an erase period for erasing wall charges
within the discharged cells.
[0127] The driving method according to the seventh embodiment
applies a first reset signal RP1 including a rising signal and a
falling signal to the scan electrode during a reset period of each
of subfields SF1-SF12 of a first frame.
[0128] Then, in case that a second frame following the first frame
is an OFF-cell, a second reset signal RP2 including only a falling
signal instead of the first reset signal RP1 is supplied to the
scan electrode during a reset period of at least one subfield (for
example, a twelfth subfield SF12 in FIG. 16) of the second
frame.
[0129] For example, if the first frame is an ON-cell, the 12 first
reset signals RP1 are supplied in the 12 subfields of the first
frame, respectively. Then, if the second frame is an OFF-cell, an
image retention pattern appears in the second frame.
[0130] When there is a movement from the first frame of the ON-cell
to the second frame of the OFF-cell, the second reset signal RP2
starts to be supplied from the last subfield SF12 of the second
frame.
[0131] In other words, if the second frame includes 12 subfields,
the first reset signal RP1 is supplied in 11 subfields of the
second frame and the second reset signal RP2 is supplied in the
remaining one subfield.
[0132] Subsequently, if a third frame following the second frame is
an OFF-cell, the first reset signal RP1 is supplied in 10-subfields
of the third frame and the second reset signal RP2 is supplied in
the remaining two subfields.
[0133] In other words, in case that a OFF-cell frame continuously
changes to OFF-cell frame, the number of second reset signals may
increase by one every time there is a movement from a frame to a
next frame.
[0134] As shown in FIG. 17, the second reset signal RP2 supplied
instead of the first reset signal RP1 in at least one subfield of
the second frame includes only the falling signal.
[0135] The falling signal is maintained at a sustain voltage Vs
being a bias voltage, and gradually falls from the sustain voltage
Vs.
[0136] since the second reset signal RP2 including only the falling
signal has a luminance of about 0 cd/m.sup.2 based on one signal as
compared with the first reset signal RP1 having a luminance of
about 0.1 cd/m.sup.2 or more based on one signal, when there is the
movement from the ON-cell first frame to the OFF-cell second frame
the application of the second reset signal RP2 can lower an image
retention level.
[0137] FIGS. 18A and 18B are diagrams for explaining in detail a
driving waveform depending on the method of driving the plasma
display apparatus according to the seventh embodiment.
[0138] As shown in FIG. 18A, the second reset signal RP2 supplied
in at least one subfield of the second frame may be supplied in
reverse order from a subfield of the highest gray level weight.
[0139] For example, if one frame includes 12 subfields and a
subsequent frame of a first frame of an ON-cell is an OFF-cell, the
second reset signal RP2 is supplied during a reset period of a last
subfield SF12 of the subsequent frame.
[0140] If a subsequent frame of a frame of an OFF-cell is an
OFF-cell, the second reset signal RP2 is supplied during a reset
period of a last subfield SF12 of the subsequent frame and an
eleventh subfield SF11 in reverse order from the last subfield
SF12. Accordingly, the increasing number of frames of an OFF-cell
is proportional to the increasing number of second reset signals
RP2.
[0141] On the other hand, if a subsequent frame of a frame of an
OFF-cell is an ON-cell, the first reset signal RP1 is supplied in
all subfields of the subsequent frame.
[0142] When an OFF-cell frame continuously moves to an OFF-cell
frame, the number of first reset signals RP1 is reduced and the
number of second reset signals RP2 increases. However, at least one
first reset signals RP1 may be supplied during one frame.
[0143] For example, in case that all of second to fifteenth frames
following a first frame of an ON-cell are an OFF-cell, the first
reset signals RP1 is supplied in one subfield of the eleventh frame
and the second reset signals RP2 is supplied in the remaining 11
subfields of the eleventh frame. Subsequently, the second reset
signals RP2 is not supplied in all subfields of the twelfth frame
of the OFF-cell. In the same way as the eleventh frame, the first
reset signals RP1 is supplied in one subfield of the twelfth frame
and the second reset signals RP2 is supplied in the remaining 11
subfields of the twelfth frame.
[0144] As above, since the second reset signal RP2 is supplied in
reverse order from a subfield of the highest gray level weight, the
generation of an erroneous discharge is prevented and time required
in removing dark image retention is reduced.
[0145] The second reset signal RP2 may be supplied in another way.
This will be described with reference to FIG. 18B.
[0146] As shown in FIG. 18B, every time there is a movement from a
frame to a next frame, the second reset signal RP2 supplied in at
least one subfield of the second frame may be supplied irrespective
of the order of subfield.
[0147] For example, if each frame includes 12 subfields and a
subsequent frame of a first frame of an ON-cell is an OFF-cell, the
second reset signal RP2 may be supplied during a reset period of a
last subfield SF12 of the subsequent frame, and the second reset
signal RP2 may be supplied during a reset period of a tenth
subfield SF10 of the subsequent frame.
[0148] Subsequently, if a subsequent frame of a frame of an
OFF-cell is an OFF-cell, the second reset signal RP2 may be
supplied during a reset period of a third subfield SF3 of the
subsequent frame. Accordingly, the increasing number of frames of
an OFF-cell is proportional to the increasing number of second
reset signals RP2.
[0149] On the other hand, when there is a movement from an OFF-cell
frame to an ON-cell frame, the first reset signal RP1 is supplied
in all subfields of the ON-cell frame.
[0150] Accordingly, the generation of an erroneous discharge is
prevented and time required in removing dark image retention is
reduced.
[0151] The foregoing embodiments and advantages are merely
exemplary and are not to be construed as limiting the present
invention. The present teaching can be readily supplied to other
types of apparatuses. The description of the foregoing embodiments
is intended to be illustrative, and not to limit the scope of the
claims. Many alternatives, modifications, and variations will be
apparent to those skilled in the art.
* * * * *